81432390 has 64 divisors (see below), whose sum is σ = 214099200. Its totient is φ = 19699584.

The previous prime is 81432367. The next prime is 81432409. The reversal of 81432390 is 9323418.

It is a super-2 number, since 2×81432390² = 13262468282224200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 21241 + ... + 24779.

It is an arithmetic number, because the mean of its divisors is an integer number (3345300).

Almost surely, 2^81432390 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81432390, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (107049600).

81432390 is an abundant number, since it is smaller than the sum of its proper divisors (132666810).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81432390 is a wasteful number, since it uses less digits than its factorization.

81432390 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3621.

The product of its (nonzero) digits is 5184, while the sum is 30.

The square root of 81432390 is about 9023.9896941431. The cubic root of 81432390 is about 433.4433993914.

The spelling of 81432390 in words is "eighty-one million, four hundred thirty-two thousand, three hundred ninety".